1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a display device and a driving method thereof, and more particularly, to a display device and a driving method thereof which drives a light emitting diode (LED) with high efficiency.
2. Description of the Related Art
An LED emits light when a voltage is applied in a forward direction. The LED employs electroluminescence effects and its light intensity is determined by an amount of current flowing through the LED. If the current exceeds a maximum rated current, the life time of the LED may become short and the LED may be damaged. Like other general diodes, the LED has a polarity and is turned on by applying a constant voltage from cathode to anode. When voltage is low, current barely flows and light is not emitted. Once the voltage reaches a certain level or higher, the current flows fast with respect to the rising voltage and the light is emitted in proportion to the amount of current. The voltage is called a forward voltage drop. The LED has a higher forward voltage drop compared to the general diodes. When the LED is used as a backlight for a display device, the display device needs an LED driving circuit to drive the LED and a pulse width modulation (PWM) dimming switch to adjust a brightness of the LED, and a metal oxide semiconductor field-effect transistor (MOSFET) is used as a switching element. The LED driving circuit includes the switching element, a PWM controller, an inductor, a capacitor to store power, and a diode to bypass the power stored in the inductor to the capacitor.
A backlight for a display panel may utilize a plurality of LEDs as a light source. Accordingly, a number of the LED driving circuits and the PWM dimming switches increases as the number of the LED increases. This may cause a switching loss from the switching element and may require many more elements including inductors. Thus, the circuits may become quite large and costly.